1. Field of the Invention
The present invention relates to a sliding resistive element layer and particularly to a tilt sensor for a vehicle steering shaft for controlling the angle of a steering shaft for a vehicle.
2. Description of Prior Art
A prior art technique for controlling the angle of a steering shaft for a vehicle is shown in FIG. 4. A switching end piece on a rotational shaft, rotated according to the angle of a handle, is provided on a tilt sensor 31 which determines the angle of a steering shaft 30. A switching end piece is contacted with a fixed contact formed on a base plate and a sensor for outputting the angle of the handle in digital form. However, the digital tilt sensor only detects ON-OFF conditions. Accordingly, it will not be fatal if, for example, dust enters into the case of the sensor device and the fixed contact is interrupted. Therefore, the structure of the case is relatively simple and is utilized for a tilt sensor in which size of the device is small and attaching positions of the device are limited, however, there is a problem in that detection of continuous volume change can not be performed.
On the other hand, continuous detection can be performed in an analog type sensor device in which a sliding member is provided on a resistive element and a current collector in order to obtain an output. Accordingly, precautions must be taken to prevent the resistive element being interrupted by dust invading from the outside and/or deformed by the outside heat. The case of such an analog sensor is required to be of airtight construction which creates a problem in that the whole sensor is of a large size. As a result, although the analog type is desirable as a tilt sensor of a vehicle steering shaft, it has not been used.